[Scip] Primal solution is not accepted because of fixings during presolving.

[Daniel Karch]

Hi,

I have written a branching rule that is sometimes able to construct a
primal solution to
my problem, and I want to add that solution via SCIPaddSol. However, for
some variables
SCIPsetSolVar fails with something like

ERROR: cannot set solution value for variable <t_psi_e_9_0> fixed to -0 to
different value 1

I have found out that the variable is fixed to zero during presolving by
presol_dualfix. How can I
prevent this from happening? I use SCIPaddVarLocks in my constraint
handlers to keep variables
from being rounded down, but there I have to provide the parameters
nlocksdown and nlocksup,
that I don't have available now. I don't really know on what grounds SCIP
decides which variables
it can fix, and it may be that fixing that variable does not exclude all
optimal solutions, but in my
situation it is inconvenient that it excludes feasible solutions that I
want to add.

Best regards,

  Daniel
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